Multi-layer assembly for fluid and vapor handling and containment systems

ABSTRACT

A multi-layer assembly for fluid and vapor handling and containment systems. The multi-layer tubing assembly comprises an extrudable layer of conductive fluoropolymer, a layer of modified fluoropolymer containing a reactive group extruded around the layer of conductive fluoropolymer and a layer of polar polymer extruded around the layer of modified fluoropolymer. The layer of modified fluoropolymer is bonded to the layer of polar polymer.

BACKGROUND OF THE INVENTION

This application is a continuation-in-part of copending application Ser.No. 09/376,511 filed on Aug. 18, 1999, which is a continuation-in-partof Ser. No. 09/326,719 filed on Jun. 7, 1999, which is acontinuation-in-part of Ser. No. 08/676,728 filed on Jul. 8, 1996 nowU.S. Pat. No. 5,931,201, which is a continuation-in-part of Ser. No.08/593,068, filed on Jan. 29, 1996 now U.S. Pat. No. 5,934,336.

The present invention relates to multi-layer tubing for fluid and vaporhandling systems. More specifically, it relates to a low cost and highperformance flexible multi-layer tubing for use in brake and fuel linesystems which has high mechanical and burst strength and low permeation.

Tubing assemblies for the transport of liquids and vapors are well knownin the art. In fuel-line applications, tubing assemblies are exposed toa variety of deleterious and harmful conditions. The tubing is in nearlyconstant contact with fuel and other automotive fluids and additives.Also, there are external environmental factors such as stone impact andcorrosive media (such as salt) to consider. Furthermore, enginetemperatures often rise to extremely high levels, and, in cold climates,there is exposure to extremely low temperatures as well.

This abundance of considerations has led to design of tubing assemblieshaving multiple layers. The materials of each layer have specific, andpreferably complementary, properties. Inner tubing layers, for example,are typically designed to be resistant to permeation by liquids andgases, while outer layers possess mechanical strength and shockresistance.

The art contains numerous examples of multi-layer tubing assemblies.U.S. Pat. No. 3,561,493 to Maillard discloses a tubing assembly havingtwo coextruded layers of different plastics, and a coextruded layer ofadhesive therebetween. The layers are chosen from plastics havingcomplementary properties. U.S. Pat. No. 4,643,927 to Luecke et al.discloses a tubing assembly having a central barrier layer ofpolyvinylidene chloride that is relatively gas impermeable. The barrierlayer is surrounded by inner and outer adhesive layers which in turn aresurrounded by inner and outer surface layers of polyethylene thatprotect the central barrier layer from degradation. U.S. Pat. No.4,887,647 to Igarishi et al. shows a multi-layer tubing assembly havingan inner fluororubber layer that prevents degradation due to amine-typeadditives and also exhibits improved adhesion to an outside rubberlayer. U.S. Pat. No. 5,038,833 to Brunnhofer discloses a tubing assemblyhaving a protective outer polyamide layer, a middle alcohol barrierlayer of polyvinyl-alcohol, and an inner water barrier layer ofpolyamide. U.S. Pat. No. 5,076,329 to Brunnhofer shows a five-layertubing assembly having outer, inner and middle layers of nylon, andintermediate bonding and solvent-blocking layers.

Another requirement for fuel lines is provision for discharge ofinternal static electricity. Accumulated, undissipated electric chargecan eventually cause a breach in a fuel line. U.S. Pat. Nos. 3,166,688to Rowand et al. and 3,473,087 to Slade disclose polytetrafluoroethylene(PTFE) tubing assemblies having electrically conductive inner layers tofacilitate dissipation of static electrical energy.

More recent developments in multi-layer tubing design have beenmotivated by governmental regulations limiting permissible hydrocarbonemissions. It is known that fluoropolymers exhibit good permeationresistance to hydrocarbon fuels. Hence, recent multi-layer tubingassemblies have usually included at least one permeation-resistantfluoropolymer layer. Difficulties have been encountered, however, infinding a commercially viable design. Multi-layer tubing assembliesutilizing fluoropolymers tend to be rigid and inflexible, particularlyat low temperatures. Fluoropolymers having strong mechanical propertiestypically do not bond well with other non-fluoropolymers. Conversely,fluoropolymers exhibiting good bondability (polyvinylidene fluoride(PVDF), in particular) tend to be mechanically weak.

U.S. Pat. No. 5,383,087 to Noone et al. is a recent example. It includesan outer impact-resistant polyamide layer, an intermediate bondinglayer, an inner permeation-resistant PVDF layer, and an innermostconductive PVDF layer for dissipation of electrostatic charge. Alllayers are coextruded. The innermost conductive layer exhibits anexceptional electrostatic dissipation capacity in the range of 10⁻⁴ to10 ⁻⁹ ohm/cm². Materials possessing such extremely high conductivity,however, are typically metallic or brittle plastic. Consequently, theyare difficult to extrude and also exhibit poor mechanical properties.Furthermore, most of the fluoropolymers disclosed in the '087 patentbond poorly with dissimilar polymers.

The fluoropolymer bonding problem is addressed in U.S. Pat. No.5,419,374 to Nawrot et al. Nawrot et al. disclose a multi-layercoextruded tubing assembly having an outer layer of polyamide 12, aninner PVDF layer, and a middle adhesion binder layer (a mixture ofpolyurethane and ethylene/vinyl acetate copolymer). Though, as discussedabove, PVDF demonstrates better adhesion to the polyamide layer, PVDFmulti-layer tubing suffers from poor cold impact resistance. This is dueto the fact that PVDF becomes brittle at low temperatures.

Other high performance fluoropolymers, such as ethylenetetrafluoroethylene (ETFE), exhibit better cold impact resistance butagain, have experienced bonding problems. One approach in the art hasbeen to pretreat the ETFE surface using methods such as chemicaletching, plasma discharge or corona discharge. European PatentApplication publication no. 0 551 094, for example, discloses amulti-layer tubing assembly in which an inner ETFE layer is treated bycorona discharge to enhance bonding to an outer polyamide layer.Similarly, PCT international application WO 95/23036 treats an innerETFE layer with plasma discharge to achieve better bonding with an outerthermosetting elastomer layer. In the same vein, U.S. Pat. No. 5,170,011etches a fluorocarbon inner layer to promote better bonding with apolyamide outer layer. These approaches, too, have their problems.Pretreatment processes such as corona and plasma discharge are expensiveand can be environmentally hazardous. Furthermore, in many cases (suchas with corona treatment), only temporary bonding is achieved anddelamination may occur with aging.

Another approach has been to utilize multi-layer tubing assemblieshaving fluoroelastomer permeation-resistant layers andnon-fluoroelastomer cover layers. U.S. Pat. Nos. 4,842,024, 4,905,736,5,093,166 and 5,346,681 are exemplary. More recently, fluoropolymershave been used as a permeation-resistant layer along withnon-fluoroelastomers or polyolefin thermoplastic elastomers as a coverlayer. These approaches, however, require a two-step cross-headextrusion process and may also require a vulcanization process. Suchprocesses are expensive and slow, and the mechanical strength and coldimpact resistance of the resulting tubing is poor.

Often, there is need for a reinforcement layer in the tubing as well.The art contains numerous examples of multi-layer tubings which includereinforcement layer(s). U.S. Pat. Nos. 4,196,464, 4,330,017 and4,759,338 disclose reinforced flexible tubings which have a fiberbraiding or filament winding between elastomer layers. The fiberbraiding and/or filament winding processes used to make these tubingsare slow and expensive. Also, use of elastomers entails a time consumingvulcanization process conducted at high temperatures which may beenvironmentally hazardous.

U.S. Pat. Nos. 5,142,782, 5,142,878 and 5,170,011 disclose reinforcedtubings which include a fiber glass braiding layer over a layer offluoropolymer such as PTFE (polytetrafluoroethylene). The processesinvolved in making these tubings are also expensive and time consuming,typically involving the multiple steps of: (1) sintering and extrudingan inner PTFE tubing layer; (2) applying a braided reinforced glassfiber layer over the inner layer; (3) dispersing a PTFE resin andcarrier fluid into the reinforcing layer; and (4) sintering theassembled tubing.

SUMMARY OF THE INVENTION

This invention relates to a multi-layer assembly for fluid and vaporhandling and containment systems. The multi-layer tubing assemblycomprises an extrudable layer of conductive fluoropolymer, a layer ofmodified fluoropolymer containing a reactive group extruded around thelayer of conductive fluoropolymer and a layer of polar polymer extrudedaround the layer of modified fluoropolymer. The layer of modifiedfluoropolymer is bonded to the layer of polar polymer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention is a four-layer tubingassembly for use in liquid fuel-line applications. It includes anextruded innermost semi-conductive fluoropolymer layer. Thefluoropolymer is made semi-conductive by mixing it with 1% to 10% byweight of conductive carbon black. Metallic conductive fillers such assilver, copper or steel may also be utilized. It has a surfaceresistivity in the range of about 10³ to 10⁸ ohm/sq. Suitablefluoropolymers for inner layer include but are not limited to ethylenetetrafluoroethylene, fluorinated ethylene propylene,hexafluoropropylene, perfluoromethyvinylether, chlorotrifluoroethylene,ethylene chlorotrifluoroethylene, tetrafluoroethylenehexafluoropropylene vinylidene, perfluoroalkoxy, polyvinylindene,polytetrafluoroethylene, and copolymers, blends and mixtures thereof.

An inner permeation-resistant fluoropolymer layer coextrudable attemperatures below 600 degrees Fahrenheit is coextruded with andsurrounds the innermost semi-conductive layer. The importance of thislayer being extrudable at temperatures below 600 degrees Fahrenheitresides in the fact that the materials contained in the cover and/orouter layers, such as polyamides, must be extruded at temperatures below600 degrees Fahrenheit. Temperatures above 600 degrees Fahrenheit mayliquefy materials such as polyamides and make them unsuitable forextrusion. Fluoropolymers suitable for the permeation-resistant layerare the same as those fluoropolymers identified as suitable for thesemi-conductive layer.

An adhesive layer is coextruded around the inner permeation-resistantlayer. The adhesive is a polymer blend or alloy that has a multiphasemorphology wherein one phase is compatible or miscible with thefluoropolymer utilized in the inner tubing layers, and another phase iscompatible or miscible with the multiphase polymer utilized in the coverlayer. Morphology development and mechanisms of phase separation inpolymer alloys and blends is known and is described in the inventor'sprior art publication, “Morphology and Property Control via PhaseSeparation or Phase Dissolution during Cure in Multiphase Systems”,Advances in Polymer Technology, Vol. 10, No. 3, pp. 185-203 (1990). Useof polymer blends and alloys having multiphase morphology is alsodescribed in the inventor's prior art publications, H. S.-Y. Hsich,Proc. 34^(th) Int. SAMPE Symp., 884 (1989), H. S.-Y. Hsich, J Mater.Sci., 25, 1568 (1990), H. S.-Y. Hsich, Polym. Eng. Sci., 30, 493 (1990).

The material for forming the adhesive layer is a polymer blend or alloythat has a multi-phase morphology wherein one phase is compatible ormiscible with fluoropolymer and another phase is compatible or misciblewith polyamides. To obtain sufficient bonding between each phase of theadhesive layer with the adjoining layers, at least 25% volume fractionof one phase is miscible with the polymer for forming one of theadjoining layer and at least 25% volume fraction of a second phase ismiscible with the polymer for forming the other adjoining layer.

A flexible multiphase polymer cover layer is coextruded around theadhesive layer. The multiphase polymer has at least two glass transitiontemperatures in which their morphology and property can be manipulatedby a thermodynamic process to create the desired damping characteristic.This concept of morphology control through a thermodynamic process tocreate the desired damping characteristic is also described in theinventor's prior art publications cited above. Suitable multiphasepolymers include polymer blends or alloys of polyamides, polyesters,polyurethane and matallocene polyolefins. The flexible multiphasepolymer can be formed to be rubber-like without the requirement ofvulcanization. These rubber-like multiphase polymers have hardnesses inthe range of Shore A 50-98 and tensile strengths in the range of3000-6000 psi (20-40 MPa). Alternatively, the flexible multiphasepolymers can be formed to be plastic-like having higher hardnesses andtensile strengths than the rubber-like multiphase polymers.

A desirable morphology and mechanical properties of the polymer blendsor alloys for forming the adhesive layer and the cover layer ofmultiphase polymers can be further improved by blending two or moreimmiscible polymers with a compatibilizer which will consequently resultin improved adhesive strength. Furthermore, during the coextrusionprocess of the multi-layer hose or tubing, the rheological properties ofthe polymer blends or alloys can be properly modified to allow thematerial for forming the adhesive layer or the cover layer of multiphasepolymers to obtain proper viscosity and elasticity to achieve theoptimal property for extrusion. Such materials for compatibilizers andrheology modifiers include but are not limited to organomers,organometallics, organophosphates, silanes, acrylate modifiedpolyolefins, acrylate modified fluoropolymers, acrylate derivativemodified polyolefins, acrylate derivative modified fluoropolymers,fluoroelastomers and mixtures thereof. To obtain optimal adhesivestrength and proper viscosity and elasticity for extrusion, the polymerblends or alloys having a multi-phase morphology should comprise 0.5% to20% of compatibilizers and rheology modifiers by weight.

The multiphase polymer for forming the outer layer may have a non-foamedstructure or a foamed structure. A foamed multiphase polymer offers thetubing assembly the same degree of strengths as a non-foamed multiphasepolymer, yet the usage of foamed multiphase polymer for forming theouter layer significantly reduces the weight of the tubing compared tothe non-foamed multiphase polymer. This reduction in weight is due tothe presence of void spaces in the multiphase polymer formed during thefoaming process.

The foaming of the multiphase polymer is caused by the addition of ablowing agent into the multiphase polymer. Examples of such blowingagents include but are not limited to azodicarbonamides, hydrazinederivatives, semi-carbazides, tetrazoles, benzoxazines and mixturesthereof. The blowing agent is mixed with the multiphase polymer justprior to the extrusion process. Following the extrusion of theouter-layer, the blowing agent will cause the multiphase polymer toexpand or foam, thus creating void spaces within the outer layer.

A second embodiment of the present invention is a three-layer tubingassembly for use in liquid fuel-line applications. It includes anextruded inner semi-conductive and permeation-resistant fluoropolymerlayer. The fluoropolymer is made semi-conductive by mixing it with 1% to10% by weight of conductive carbon black. It has a surface resistivityin the range of about 10³ to 10⁸ ohm/sq. The fluoropolymer can undergoextrusion at temperatures below 600 degrees Fahrenheit. Suitablefluoropolymers are the same as those fluoropolymers identified assuitable in the first embodiment.

An adhesive layer is coextruded around the inner permeation-resistantlayer. The adhesive, as in the first embodiment, is a polymer blend oralloy that has a multiphase morphology wherein one phase is compatibleor miscible with the utilized fluoropolymer, and another phase iscompatible or miscible with the utilized multiphase polymer. Amultiphase polymer cover layer is coextruded around the adhesive layer.Suitable multiphase polymers are the same as those identified assuitable for the first embodiment.

A third embodiment of the present invention is a three-layer tubingassembly for use in vapor fuel-line applications. It includes anextruded inner permeation-resistant fluoropolymer layer. Thefluoropolymer is extrudable at temperatures below 600 degreesFahrenheit. Suitable fluoropolymers are the same as those identifiedabove.

An adhesive layer is coextruded around the inner permeation-resistantlayer. The adhesive, as in the first and second embodiments, is apolymer blend or alloy that has a multiphase morphology wherein onephase is compatible or miscible with fluoropolymer and another phase iscompatible or miscible with a multiphase polymer.

A multiphase polymer cover layer is coextruded around the adhesivelayer. Suitable multiphase polymers are the same as those identifiedabove.

A fourth embodiment of the present invention is a four-layer tubingassembly for use in vapor fuel-line applications. The fourth embodimentis the same as the third embodiment but includes an additional,outermost plastic layer. Suitable plastics for this outermost layerinclude polyamides and polyesters.

The fifth embodiment of the present invention comprises a reinforcedflexible tubing including an inner layer of fluoropolymer, a reinforcingfabric ribbon layer and a cover layer. Suitable fluoropolymers for theinner layer include but are not limited to ethylene tetrafluoroethylene,fluorinated ethylene propylene, hexafluoropropylene,perfluoromethyvinylether, chlorotrifluoroethylene, ethylenechlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylenevinylidene, perfluoroalkoxy, polyvinylindene, polytetrafluoroethylene,and copolymers, blends and mixtures thereof.

The cover layer may be comprised of the same material as the inner layeror it may be comprised of multiphase polymers. The multiphase polymersfor forming the cover layer are the same as those multiphase polymersidentified as suitable for forming the cover layer in the firstembodiment.

A reinforcing fabric ribbon layer is disposed between the inner layerand cover layer. The tubing is manufactured by simultaneously wrappingthe reinforcing fabric ribbon and extruding the cover layer around theinner fluoropolymer tubing layer. Expensive and time consuming prior artprocess steps such as braiding, dispersing binders or adhesive,sintering or vulcanization are not needed.

A sixth embodiment of the present invention is a three-layer tubingassembly for use in liquid fuel-line applications. It includes anextruded inner conductive and permeation-resistant metallic layer.Suitable metals for forming the metallic layer include but are notlimited to copper, aluminum or aluminum alloy. The molten metal, or theutilized metal in its liquid state, is extruded to form the metalliclayer.

After the metallic layer has been sufficient cooled, a thermoplasticprotective layer is extruded around the metallic layer. Suitablethermoplastics for the protective layer include but are not limited topolyamides and polyesters. A nultiphase polymer cover layer iscoextruded around the thermoplastic protective layer. Suitablemultiphase polymers for forming the cover layer are the same as thoseidentified as suitable for forming the cover layer in the firstembodiment.

A seventh embodiment of the present invention is a two-layer tubingassembly for use in vapor fuel-line applications. It includes anextrudable inner permeation-resistant thermoplastic layer. Suitablethermoplastics for forming the inner layer include but are not limitedto fluoropolymers, polyamides, polyester, polyurethanes, polyvinylchloride, polyketones, polyolefins and mixtures thereof.

A multiphase polymer cover layer, capable of bonding to thethermoplastic inner layer, is coextruded around the thermoplastic layer.Suitable multiphase polymers for forming the cover layer are the same asthose identified for forming the cover layer in the first embodiment.

An eighth embodiment of the present invention is a three-layer tubeassembly for use in vapor fuel-line applications. It includes aninnermost layer of nanocomposite, a middle layer of adhesive and a coverlayer of multiphase polymer.

Polymer nanocomposites are the combination of a polymer matrix resin andinorganic particles. The resulting nanocomposite particle has at leastone dimension (i.e., length, width or thickness) in the nanometer sizerange.

The benefits of using nanocomposites for forming the inner layer includeefficient reinforcement with minimum loss of ductility and impactstrength, heat stability, flame resistance, improved gas barrierproperties, improved abrasion resistance, reduced shrinkage and residualstress, altered electronic and optical properties. The benefits of usingnanocomposites for forming the inner layer result from the compactnessof the nanocomposite particles. For instance, since the particles arevery small, the voids between the particles are also very small, thusreducing gas leakage through the wall of the tubing formed ofnanocomposite.

A number of inorganic particles can be used for forming thenanocomposite. Such inorganic particles include but are not limited toclay and montmorillonite. The use of clay for forming the nanocompositeis preferred since clay is the inorganic particle easiest to work with.To obtain the desirable properties of the nanocomposite, should clay beused as the inorganic particles, the nanocomposite should comprise 0.1%to 10% of clay by weight.

A wide variety of polymers can be used as the matrix resins for formingthe nanocomposites. The polymer which can used as the matrix resinsinclude but are not limited to polyamides, polystyrene, polyetherimide,acrylate and methacrylate oligomers, polymethyl methacrylate,polyproylene, polyethylene oxide, epoxy, polyimide, unsaturatedpolyester and mixtures thereof.

An adhesive layer is coextruded around the inner layer of nanocomposite.The adhesive, as in the first embodiment, is a polymer blend or alloythat has multiphase morphology wherein one phase is compatible ormiscible with the nanocomposite forming the inner layer and anotherphase is compatible or miscible with the multiphase polymer forming thecover layer.

A multiphase polymer cover is coextruded around the adhesive layer.Suitable multiphase polymers are the same as those identified in thefirst embodiment.

A ninth embodiment of the present invention is a three-layer tubeassembly for use in vapor fuel-line applications. It includes an innerlayer of nanocomposite, a middle layer of adhesive and a cover layer ofthermoplastic. Suitable nanocomposites for forming the inner layer arethe same as those identified as suitable for the eighth embodiment.

An adhesive layer is coextruded around the inner layer of nanocomposite.The adhesive, as in the first embodiment, is a polymer blend or alloythat has multiphase morphology wherein one phase is compatible ormiscible with the nanocomposite forming the inner layer and anotherphase is compatible or miscible with the thermoplastic forming the coverlayer.

A cover layer of thermoplastic is coextruded around the adhesive layer.Suitable thermoplastics for forming the cover layer include but are notlimited to fluoropolymers, polyamides, polyester, polyurethanes,polyvinyl chloride, polyketones, polyolefins and mixtures thereof. Thethermoplastic can be formed having a non-foamed structure or a foamedstructure. The process for foaming the thermoplastic is the same processfor foaming the multiphase polymer as disclosed in the first embodiment.

A tenth embodiment of the present invention is a two-layer tubingassembly for use in vapor fuel-line applications. It includes an innerlayer of nanocomposite. Suitable nanocomposites for forming the innerlayer are the same as those identified for the eighth embodiment.

A multiphase polymer cover layer, capable of bonding to thenanocomposite for forming the inner layer, is coextruded around theinner layer. Suitable multiphase polymers for forming the cover layerare the same as those identified as suitable for forming the cover layerin the first embodiment.

An eleventh embodiment of the present invention is a two-layer tubingassembly for use in fuel-line applications or a two-layer containerassembly for use in fuel containment applications. It includes an innerlayer of a modified fluoropolymer containing a reactive group. Examplesof such fluoropolymers to be modified include but are not limited toethylene tetrafluoroethylene, fluorinate ethylene propylene,hexafluoropropylene, perfluoromethyvinylether, chlorotrifluoroethylene,ethylene chlorotrifluoroethylene, tetrafluoroethylenehexafluoropropylene vinylidene, perfluoromethyvinylether,chlorotrifluoroethylene, ethylene chlorotrifluoroethylene,tetrafluoroethylene hexafluoropropylene vinylidene, perfluoroalkoxy,polyvinylidene, polytetrafluoroethylene, and copolymers, blends andmixtures thereof.

An outer layer of a polar polymer is extruded around and bonded to theinner layer of the modified fluoropolymer. Examples of such polarpolymers include but are not limited to polyamides, modified polyamides,polyamide alloys and polyamide blends.

One difficulty associated with bonding fluoropolymer with a polarpolymer is that fluoropolymer is not polar. To improve adhesion ormiscibility of two dissimilar polymers, the present invention modifiesone or both of the polymers to provide favorable specific interactionsbetween two polymers leading to a negative contribution to the Gibbsfree energy of mixing. These interactions include hydrogen bonding,donor-acceptor interactions, dipole-dipole interactions, anion-cationinteractions, ion-dipole interactions, and intrachain repulsion.

The fluoropolymer of the present invention is modified by attaching adifferent function group which increases the polarity of thefluoropolymer. More specifically the fluoropolymer is modified tocontain a reactive group which is more polar than the functional groupthe reactive group replaces. Examples of such reactive groups includebut are not limited to acrylate, maleic anhydride, isocyanurate andmixtures thereof.

A twelfth embodiment of the present invention is a three-layer tubingassembly for use in fuel-line applications or a three-layer containerassembly for use in fuel containment applications. It includes anextruded inner semi-conductive and permeation-resistant fluoropolymerlayer. The fluoropolymer is made semi-conductive by mixing it with 0.1%to 10% by weight of conductive carbon black. It has a surfaceresistivity in the range of about 10³ to 10⁸ ohm/sq. Suitablefluoropolymers are the same as those fluoropolymers identified assuitable in the first embodiment.

A layer of modified fluoropolymer containing a reactive group isextruded around the inner layer of conductive fluoropolymer. Suitablemodified fluoropolymers are the same those modified fluoropolymersidentified in the eleventh embodiment. A layer of polar polymer isextruded around and bonded to the modified fluoropolymer. Suitable polarpolymers are the same as those polar polymers identified as suitable inthe eleventh embodiment.

A thirteenth embodiment of the present invention is a two-layer tubingassembly for use in fuel-line applications or a two-layer containerassembly for use in fuel containment applications. It includes an innerlayer of a conductive polymer comprising a polymer and a conductivefiller. Suitable polymer for mixing with the conductive filler includebut are not limited to fluoropolymers, polyamides, polyimides,polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals,phenolic resins, polyketones, polyvinyl chloride, polyolefins and theircopolymers, blends, and mixtures thereof. Suitable fluoropolymersinclude but are not limited to ethylene tetrafluoroethylene, fluorinateethylene propylene, hexafluoropropylene, perfluoromethyvinylether,chlorotrifluoroethylene, ethylene chlorotrifluoroethylene,tetrafluoroethylene hexafluoropropylene vinylidene,perfluoromethyvinylether, chlorotrifluoroethylene, ethylenechlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylenevinylidene, perfluoroalkoxy, polyvinylidene, polytetrafluoroethylene,and copolymers, blends and mixtures thereof. A layer of a polar polymeris extruded around and bonded to the layer of conductive polymer.Suitable polar polymers are the same as those polar polymers identifiedto be suitable in the eleventh embodiment.

According to the present invention, another method to improveconductivity of a fluoropolymer is to add conductive filler to thefluoropolymer. Examples of such conductive fillers include but are notlimited to mesophase pitch-based graphitic foam in particle form withextremely high electric and thermal conductivity for dissipating staticelectrically energy and thermal energy. For the purpose of thisapplication, particle form is defined as having a size from 0.1 micronto 500 micron in particle length. To obtain the desirable conductivitycharacteristic, the conductive fluoropolymer should comprise 0.1% to 15%by weight conductive filler.

A fourteenth embodiment of the present invention is a three-layer tubingassembly for use in fuel-line applications or a three-layer containerfor use in fuel containment applications. It includes an extruded innerconductive and permeation-resistant floropolymer layer. Thefluoropolymer is made conductive by mixing it with 0.1% to 15% by weightconductive filler. Examples of such conductive fillers include but arenot limited to mesophase pitch-based graphitic foam in particle formwith extremely high electric and thermal conductivity for dissipatingstatic electrically energy and thermal energy. The conductive polymerhas a surface resistivity in the range of about 10³ to 10⁸ ohm/sq. Alayer of a modified fluoropolymer is extruded around the inner layer ofconductive fluoropolymer. Suitable modified fluoropolymers are the samethose modified fluoropolymers identified in the eleventh embodiment. Alayer of polar polymer is extruded around and bonded to the layer ofmodified fluoropolymer. Suitable polar polymers are the same as thosepolar polymers identified to be suitable in the eleventh embodiment.

A fifteenth embodiment of the present invention is a three-layer tubingassembly for use in fuel-line applications or a three-layer containerfor use in fuel containment applications. It includes an inner layer ofpolymer having good permeation or chemical resistance. A middle-layer ofdamping polymeric material extruded around or applied on the innerpolymeric layer and an outer polymer extruded around the damping layer.

The inner polymer layer and the outer polymer layer may be the samepolymer or they may be different polymers. Examples of such polymers forforming the inner polymer layer and/or the outer polymer layer includebut are not limited to fluoropolymers, polyamides, polyimides,polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals,phenolic resins, polyketones, polyvinyl chloride, polyolefins and theircopolymers, blends and mixtures thereof.

The polymer for forming the inner polymeric layer and/or the outerpolymeric layer may also be conductive for dissipating static electricenergy and thermal energy. The conductive polymer comprises a polymerresin and a conductive filler. Examples of such polymer resins includebut are not limited to elastomers, thermoplastic elastomers, blockcopolymers, fluoropolymers, polyamides, polyimides, polyesters, epoxies,polyurethanes, polyphenylene sulfides, polyacetals, phenolic resins,polyketones, polyvinyl chloride, polyolefins, and copolymers, blends andmixtures thereof. The conductive filler is made from mesophasepitch-based graphitic foam in particle form with extremely high electricand thermal conductivity.

The middle layer of polymeric material has a high damping factor (theratio of the loss modulus over the storage modulus) but with a moduluslower than the modulus of the material forming the inner-layer and thematerial forming the outer-layer. The multi-layer assembly with aconstrained damping layer structure has a much higher damping efficiencythan that of free damping layer structure which is without an outerlayer of high modulus material covering the damping material layer. Thedamping material layer exhibits both the capacity to store energy(elastic) and the capacity to dissipate energy (viscous). The dampingmaterial may be extruded around the inner layer or the damping materialcan be applied on the inner layer with a brush or spray. Examples ofsuch damping polymers which can be extruded include but are not limitedto fluoropolymers, polyamides, polyimides, polyesters, epoxies,polyurethanes, polyphenylene sulfides, polyketones, polyvinyl chloride,polyolefins, and copolymers, blends and mixtures thereof. Examples ofsuch damping polymers which can applied on the inner layer with a brushor spray include but are not limited to elastomers, thermoplasticelastomers, and block copolymers comprising a rigid block polymer and aflexible block polymer.

The extrudable damping polymer for forming the middle layer may have anon-foamed structure or a foamed structure. A foamed structure increasesthe damping characteristic of the middle layer. The foaming of theextrudable damping polymer is caused by the addition of a blowing agentinto the damping polymer. Examples of such blowing agents include butare not limited to azodicarbonamides, hydrazine derivatives,semi-carbazides, tetrazoles, benzoxazines and mixtures thereof. Theblowing agent is mixed with the damping polymer just prior to theextrusion process. Following the extrusion of the damping polymer, theblowing agent will cause the damping polymer to expand or foam, thuscreating void spaces within the outer layer.

The damping polymeric material can also be a multiphase polymer. Themultiphase polymer has at least two glass transition temperatures inwhich their morphology and property can be manipulated by athermodynamic process to create the desired damping characteristic.Suitable multiphase polymers are the same as those identified in thefirst embodiment.

A sixteenth embodiment of the present is a three-layer tubing assemblyfor use in fuel-line applications or a three-layer container for use infuel containment applications. It is essentially the same as themulti-layer assembly identified in the fifteenth embodiment but includesan inner layer of metal rather than an inner layer of polymer. Thesixteenth embodiment includes an inner layer of metal. A middle-layer ofdamping polymeric material is extruded around or applied on the innerpolymeric layer and an outer polymer is extruded around the dampinglayer.

The metal for forming the inner layer is selected from the groupconsisting of steel, aluminum, copper and their alloys. The inner layerof metal may be treated to provide corrosion protection. Suitablematerial for treating the inner layer include but are not limited toterne (an alloy of normally 85% lead and 15% tin), zinc-rich paint,aluminum-rich paint, electroplated zinc or zinc-nickel, zinc-aluminumalloy (or also known under the trademark GALFAN), hot dip aluminum,epoxy coating, polyvinyl fluoride or polyvinyl di-fluoride coating,nylon coating and combination thereof.

Suitable damping polymers for forming the middle layer are the same asthose damping polymers identified as suitable in the fifteenthembodiment. Suitable polymer for forming the outer layer the same asthose polymers identified as suitable in the fifteenth embodiment. As inthe fifteenth embodiment, the damping polymer in the sixteenthembodiment has a high damping factor but with a modulus lower than themodulus of the material forming the inner-layer and the material formingthe outer-layer material.

Various features of the present invention have been described withreference to the above embodiments. It should be understood thatmodification may be made without departing from the spirit and scope ofthe invention as represented by the following claims.

What is claimed is:
 1. A multi-layer assembly for fluid and vapor handling and containment systems comprising: an extrudable layer of modified fluoropolymer containing a reactive group; a layer of polar polymer extruded around said layer of modified fluoropolymer; and wherein said layer of modified fluoropolymer is bonded to said layer of polar polymer.
 2. The multi-layer assembly as claimed in claim 1 wherein said polar polymer is selected from a group consisting of polyamides, modified polyamides, polyamide alloys and polyamide blends.
 3. The multi-layer assembly as claimed in claim 1 wherein said reactive group is selected from a group consisting of acrylate, maleic anhydride, isocyanurate and mixtures thereof.
 4. The multi-layer assembly as claimed in claim 1 wherein said fluoropolymer to be modified is selected from a group consisting of ethylene tetrafluoroethylene, fluorinate ethylene propylene, hexafluoropropylene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoroalkoxy, polyvinylidene, polytetrafluoroethylene, and copolymers, blends and mixtures thereof.
 5. A multi-layer assembly for fluid and vapor handling and containment systems comprising: an extrudable layer of conductive fluoropolymer containing a conductive filler; a layer of polar polymer extruded around said layer of modified fluoropolymer; and wherein said layer of modified fluoropolymer is bonded to said layer of polar polymer.
 6. The multi-layer assembly as claimed in claim 5 wherein said polar polymer is selected from a group consisting of polyamides, modified polyamides, polyamide alloys and polyamide blends.
 7. The multi-layer assembly as claimed in claim 5 wherein said conductive filler is a mesophase pitch-based graphitic foam in particle form with extremely high electric and thermal conductivity for dissipating static electrically energy and thermal energy.
 8. The multi-layer assembly as claimed in claim 5 wherein said conductive fluoropolymer comprises 0.1% to 15% by weight conductive fillers.
 9. The multi-layer assembly as claimed in claim 5 wherein said fluoropolymer to be modified is selected from a group consisting of ethylene tetrafluoroethylene, fluorinate ethylene propylene, hexafluoropropylene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoroalkoxy, polyvinylidene, polytetrafluoroethylene, and copolymers, blends and mixtures thereof.
 10. A multi-layer assembly for fluid and vapor handling and containment systems comprising: an extrudable layer of conductive fluoropolymer; a layer of modified fluoropolymer containing a reactive group extruded around said layer of conductive polymer; a layer of polar polymer extruded around said layer of modified fluoropolymer; and wherein said layer of modified fluoropolymer is bonded to said layer of polar polymer.
 11. The multi-layer assembly as claimed in claim 10 wherein said polar polymer is selected from a group consisting of polyamides, modified polyamides, polyamide alloys and polyamide blends.
 12. The multi-layer assembly as claimed in claim 10 wherein said reactive group is selected from a group consisting of acrylate, maleic anhydride, isocyanurate and mixtures thereof.
 13. The multi-layer assembly as claimed in claim 10 wherein said fluoropolymer to be modified is selected from a group consisting of ethylene tetrafluoroethylene, fluorinate ethylene propylene, hexafluoropropylene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoroalkoxy, polyvinylidene, polytetrafluoroethylene, and copolymers, blends and mixtures thereof.
 14. The multi-layer assembly as claimed in claim 10 wherein said conductive fluoropolymer has a surface conductivity of 10³ to 10⁸ ohm/sq.
 15. The multi-layer assembly as claimed in claim 10 wherein said conductive fluoropolymer comprises 0.1% to 10% by weight of conductive carbon black.
 16. The multi-layer assembly as claimed in claim 10 wherein said conductive fluoropolymer comprises a mesophase pitch-based graphitic foam in particle form with extremely high electric and thermal conductivity for dissipating static electrically energy and thermal energy.
 17. The multi-layer assembly as claimed in claim 16 wherein said conductive fluoropolymer comprises 0.1% to 15% by weight mesophase pitch-based graphitic foam in particle form.
 18. A conductive polymer for use as a conductive layer in a multi-layer assembly comprising a polymer and a mesophase pitch-based graphitic foam in particle form with extremely high electric and thermal conductivity for dissipating static electrically energy and thermal energy.
 19. The conductive polymer as claimed in claim 18 wherein said polymer is selected from the group consisting of fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals, phenolic resins, polyketones, polyvinyl chloride, polyolefins and their copolymers, blends, and mixtures thereof.
 20. The conductive polymer as claimed in claim 19 wherein said fluoropolymer is selected from a group consisting of ethylene tetrafluoroethylene, fluorinate ethylene propylene, hexafluoropropylene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoromethyvinylether, chlorotrifluoroethylene, ethylene chlorotrifluoroethylene, tetrafluoroethylene hexafluoropropylene vinylidene, perfluoroalkoxy, polyvinylidene, polytetrafluoroethylene, and copolymers, blends and mixtures thereof.
 21. The multi-layer assembly as claimed in claim 18 wherein said conductive polymer comprises 0.1% to 15% by weight mesophase pitch-based graphitic foam in particle form.
 22. A multi-layer assembly for fluid and vapor handling and containment systems comprising: an inner layer of a polymeric material; a middle layer of a damping material surrounding said inner layer of polymeric material; an outer layer of a polymeric material surrounding said layer of damping material; and wherein said damping material has a high damping factor and a modulus lower than the modulus of said polymeric material forming said inner layer and the modulus of said polymeric material forming said outer layer.
 23. The multi-layer assembly as claimed in claim 22 wherein said inner polymeric layer has good chemical resistance.
 24. The multi-layer assembly as claimed in claim 22 wherein said polymer for forming said inner layer is selected from the group consisting of fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals, phenolic resins, polyketones, polyvinyl chloride, polyolefins and their copolymers, blends, and mixtures thereof.
 25. The multi-layer assembly as claimed in claim 22 wherein said polymer for forming said outer layer is selected from the group consisting of fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals, phenolic resins, polyketones, polyvinyl chloride, polyolefins and their copolymers, blends, and mixtures thereof.
 26. The multi-layer assembly as claimed in claim 22 wherein said damping material for forming said middle layer is selected from the group consisting of fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyketones, polyvinyl chloride, polyolefins, and copolymers, blends and mixtures thereof.
 27. The multi-layer assembly as claimed in claim 26 wherein said damping material for forming said middle layer has a foamed structure.
 28. The multi-layer assembly as claimed in claim 22 wherein said damping material for forming said middle layer is selected from the group consisting of elastomers, thermoplastic elastomers, and block copolymers comprising a rigid block polymer and a flexible block polymer.
 29. The multi-layer assembly as claimed in claim 22 wherein said damping material for forming said middle layer is a multiphase polymer.
 30. The multi-layer assembly as claimed in claim 22 wherein said polymer for forming one of said inner layer and outer layer is conductive.
 31. The multi-layer assembly as claimed in claim 30 wherein said conductive polymer comprises a polymer resin and a conductive filler.
 32. The multi-layer assembly as claimed in claim 31 wherein said conductive filler is a mesophase pitch-based graphitic foam in particle form with extremely high electric and thermal conductivity.
 33. The multi-layer assembly as claimed in claim 31 wherein said polymer resin is selected from the group consisting of elastomers, thermoplastic elastomers, block copolymers, fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals, phenolic resins, polyketones, polyvinyl chloride, polyolefins, and copolymers, blends and mixtures thereof.
 34. A multi-layer assembly for fluid and vapor handling and containment systems comprising: an inner layer of a metallic material; a middle layer of a damping material surrounding said inner layer of polymeric material; an outer layer of a polymeric material surrounding said layer of damping material; and wherein said damping material has a high damping factor and a modulus lower than the modulus of said metallic material forming said inner layer and the modulus of said polymeric material forming said outer layer.
 35. The multi-layer assembly as claimed in claim 34 wherein said metal for forming said inner layer is selected from the group consisting of steel, aluminum, copper and their alloys.
 36. The multi-layer assembly as claimed in claim 34 wherein said inner layer of metallic material is treated with a material selected from the group consisting of terne, zinc-rich paint, aluminum-rich paint, electroplated zinc or zinc-nickel, zinc-aluminum alloy, hot dip aluminum, epoxy coating, polyvinyl fluoride or polyvinyl di-fluoride coating, nylon coating and combination thereof.
 37. The multi-layer assembly as claimed in claim 34 wherein said polymer for forming said outer layer is selected from the group consisting of fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals, phenolic resins, polyketones, polyvinyl chloride, polyolefins and their copolymers, blends, and mixtures thereof.
 38. The multi-layer assembly as claimed in claim 34 wherein said damping material for forming said middle layer is selected from the group consisting of fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyketones, polyvinyl chloride, polyolefins, and copolymers, blends and mixtures thereof.
 39. The multi-layer assembly as claimed in claim 38 wherein said damping material for forming said middle layer has a foamed structure.
 40. The multi-layer assembly as claimed in claim 34 wherein said damping material for forming said middle layer is selected from the group consisting of elastomers, thermoplastic elastomers, and block copolymers comprising a rigid block polymer and a flexible block polymer.
 41. The multi-layer assembly as claimed in claim 34 wherein said damping material for forming said middle layer is a multiphase polymer.
 42. The multi-layer assembly as claimed in claim 34 wherein said polymer for forming said outer layer is conductive.
 43. The multi-layer assembly as claimed in claim 42 wherein said conductive polymer comprises a polymer resin and a conductive filler.
 44. The multi-layer assembly as claimed in claim 43 wherein said conductive filler is a mesophase pitch-based graphitic foam in particle form with extremely high electric and thermal conductivity.
 45. The multi-layer assembly as claimed in claim 43 wherein said polymer resin is selected from the group consisting of elastomers, thermoplastic elastomers, block copolymers, fluoropolymers, polyamides, polyimides, polyesters, epoxies, polyurethanes, polyphenylene sulfides, polyacetals, phenolic resins, polyketones, polyvinyl chloride, polyolefins, and copolymers, blends and mixtures thereof. 